Barrier coatings

ABSTRACT

The invention relates to a method of preventing a material from adhering to a surface. In a preferred embodiment, the material comprises weld spatter and the surface is located near a welding operation. The method comprises coating the surface with a slurry comprising a mineral material in water. The slurry contains from 10% to 70% solids by weight and not more than 5% by weight of a material that decomposes when heated to 1000° F. for one minute. The slurry is allowed to dry to form a barrier coating before the material contacts the surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser.No. 60/280,036, filed Mar. 30, 2001.

BACKGROUND OF THE INVENTION

This invention relates in general to barrier coatings, and in particularto a welding machine maintenance coating that prevents the adhesion ofweld spatter on the welding machine and other areas where weld spatteris a problem. This coating often prevents the buildup of weld slag, andwhen buildups of weld slag occur, it makes for easy clean up of weldslag off welding machines and areas where weld spatter causes a buildupof weld slag.

Automated and robotic controlled welding is often used in the assemblyof a product. In the process of welding, molten metal often flies awayfrom the welding location. This molten metal is commonly referred to asweld spatter. When this molten metal cools, it is commonly referred toas weld slag. In automated or robotic controlled spot welding, weldspatter is often produced which can fly as far as fifty feet from thewelding location. This weld spatter often flies in the same directionproducing buildups of weld slag on automated machinery. Often automatedor robotic controlled welders are manufactured to tight dimensionaltolerances and these buildups of weld slag often accumulate enough toproduce out of specification parts and/or prevent the welding machinefrom operating. This produces costly quality issues, production downtimeand requires maintenance to remove the weld slag off the weldingmachine. Weld slag is commonly removed by wire brushing, scraping,prying, chiseling, and grinding. This is often a very labor intensive,tedious, and time consuming process which often creates furtherbreakdowns on the automated welding machinery.

Currently available weld anti-spatter products are formulations usingorganic materials for release agents. A very common weld spatter releasecoating is based on soy lecithin and soybean oil or other vegetableoils. This product is often supplied in aerosol cans pressurized withmethylene chloride or CO₂. The product is typically sprayed on the metalto be welded or on the welding nozzle to prevent the adhesion of weldspatter to the nozzle. Other common weld anti-spatter materials are gelproducts that are often petrolatum or thickened lecithin or vegetableoils. Another weld anti-spatter product is described in U.S. Pat. No.4,861,392 to Grabe where a typical composition is composed as follows.5-6% micronized graphite, 51-60% limestone, 34-38% water, 0.5-1%morpholine, 0.2-0.4% polysorbate 80, 0.2-1.0% potassium alginate,0.02-1.2% Natrosol LR70, and 0.01-1.0% Kelzan. These products aresomewhat effective but have two major drawbacks. First, they are onlyeffective for a limited period mainly because they decompose. Second, inthe process of decomposition, the products produce noxious odors, fumes,and smoke. Since weld spatter is composed of molten iron metal, being atapproximately 1300° C. the weld spatter readily decomposes organicmaterials producing noxious decomposition products. Since there isusually only general ventilation in these areas, these noxious fumes canmake production workers ill. For these health and safety reasons andtheir limited time of effectiveness, the current weld-spatter productshave not gained acceptance for use as a maintenance coating forautomated welding machinery. Currently there is a need in the automatedwelding industry for an effective weld maintenance coating that willreduce or eliminate down time related to weld slag for extended periodsof time and be free of producing noxious odors.

SUMMARY OF THE INVENTION

This invention relates to a method of preventing a material fromadhering to a surface. In a preferred embodiment, the material comprisesweld spatter and the surface is located near a welding operation. Themethod comprises coating the surface with a slurry comprising a mineralmaterial in water. The slurry contains from about 10% to about 70%solids by weight and not more than about 5% by weight of a material thatdecomposes when heated to 1000° F. for one minute. The slurry is allowedto dry to form a barrier coating before the material contacts thesurface.

In another embodiment of the invention, the barrier coating binds to thesurface such that from about 50 to about 200 finger double rubs arerequired to reach the surface when the dry barrier coating is 30 micronsthick.

In another embodiment of the invention, the barrier coating dries in atime not longer than about 20 minutes when the slurry is applied as a250 micron thick wet film and with the temperature at 72° F. and airmoving over the film at 110 feet per minute.

Various advantages of this invention will become apparent to thoseskilled in the art from the following detailed description of thepreferred embodiments, when read in light of the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An effective welding machine maintenance coating for weld slag buildupwill accomplish the following:

-   1. Prevent hot weld spatter from adhering to welding machinery and    areas affected by buildup of weld slag.-   2. Provide easy removal of weld slag off machinery and other areas    were it has built up.-   3. Be effective until next scheduled maintenance time. Maintenance    schedules vary considerably and the major affectors are: how much    use the welding machinery receives and, the amount of weld spatter    produced. This ranges from daily maintenance to weekly or bi-weekly    to three months. Typically, most machinery requires maintenance    somewhere between one week to three months.-   4. Be easily applied. Automated welding machines are usually very    complex and an easy application is necessary. Spray application is    the preferred method. Brush application would be very tedious.-   5. Produce no noxious odors or fumes when hot weld spatter hits the    weld maintenance coating. Noxious fumes produced can make production    workers ill. This is a concern since most automated welding machines    are operated in areas with only general ventilation.-   6. Have quick dry time. Often the production plant only has time to    apply the maintenance coating on weekends. Ideally, the weld    maintenance coating should be dry within an hour of application.-   7. Coating should be easily removed with the weld slag for the next    application of the maintenance coating. Some methods of removing the    coating include wire brushing, scraping, wiping with a cloth wetted    with water, use of cleaning machinery such as CO₂ ice blasting    machines, steam cleaning machines, or water cleaning with pressure    washers. The property of the coating being removable and somewhat    powdery is an attribute that helps the removal of large weld spatter    build ups giving an area of release between the substrate and the    built up weld-slag. This is especially important in areas where    there is a lot of mechanical adhesion to the substrate such as    electrical cables and cooling lines. Conversely, permanent films    would not provide the easy release. In addition, permanent films    after many repeated applications would eventually build up on areas    of the machine, and over time cause the same problems as the build    up of weld slag.

It has been discovered that certain minerals or combinations of mineralswhen applied in an aqueous slurry form upon drying will form a barriercoating that meets at least most of the requirements mentioned above fora welding machine maintenance coating, and preferably substantially allof the requirements.

The present invention is a method of preventing a material from adheringto a surface. Preferably, the material is weld spatter, and the surfaceis located near a welding operation. However, the method can also beused to prevent other materials from adhering to surfaces. The methodcomprises coating the surface with a slurry comprising a mineralmaterial in water. By “mineral material” is meant one or more minerals,and preferably a combination of more than one mineral as disclosedbelow. The slurry contains from about 10% to about 70% solids by weight,and preferably from about 25% to about 40% solids by weight. The slurryis allowed to dry to form a barrier coating before the material contactsthe surface. Preferably, the slurry has a rheology that prevents it fromsagging or running on vertical surfaces when applied at a temperature of72° F.

In a first embodiment of the invention, the slurry contains not morethan about 5% by weight of a material that decomposes when heated to1000° F. for one minute, preferably not more than about 3%, and morepreferably not more than about 1%. Most preferably, the dried barriercoating has substantially no decomposition when heated to 1000° F. forone minute. Preferably, the slurry contains not more than about 5% byweight of a material that fumes or smokes when heated to 1000° F. forone minute, more preferably not more than about 3%, and more preferablynot more than about 1%. Most preferably, the dried barrier coatingproduces substantially no fumes or smoke when heated to 1000° F. for oneminute. Organic materials are examples of materials that would be likelyto decompose and produce fumes/smoke at this temperature.

Certain types of minerals are preferred for use in the slurry. In oneembodiment, the mineral solids portion of the slurry contains from about1% to about 90% by weight of minerals selected from the group consistingof aluminum tri-hydroxide, magnesium hydroxide, graphite, hexagonalboron nitride, and mixtures thereof. In another embodiment, the mineralsolids portion of the slurry contains from about 10% to about 80% byweight of minerals selected from the group consisting of sodiummagnesium aluminosilicate, diatomaceous earth, pumice, amorphous silica,and mixtures thereof. In another embodiment, the mineral solids portionof the slurry contains from about 10% to about 80% by weight of mineralsselected from the group consisting of calcium carbonate, calcined clay,delaminated kaolin clay, kaolin clay, talc, and mixtures thereof.

Other minerals and other materials are disfavored for use in the slurry.In one embodiment, the mineral solids portion of the slurry containsless than about 20% by weight of minerals selected from the groupconsisting of hydrous sodium polysilicate, sodium meta-silicatepentahydrate, and mixtures thereof. In another embodiment, the slurrycontains less than about 2% by weight of a material selected from thegroup consisting of zinc phosphate, aluminosilicate, calciummetasilicate, and mixtures thereof. In another embodiment, the slurrycontains less than about 5% by weight of a material selected from thegroup consisting of wax emulsion, lecithin, ethyleneoxide/propyleneoxideblock polymers, ethyl polysilicates, and mixtures thereof. Preferably,the slurry contains substantially no organic solvent.

In a second embodiment of the invention, the barrier coating binds tothe surface such that from about 50 to about 200 finger double rubs (asdescribed below) are required to reach the surface when the dry barriercoating is 30 microns thick. If fewer double rubs are required, thebarrier coating is too easy to remove from the surface so that it wouldnot be effective for a desired length of time. If more double rubs arerequired, the barrier coating adheres to strongly to the surface andcannot be easily removed.

In a third embodiment of the invention, the barrier coating dries in atime not longer than about 20 minutes when the slurry is applied as a250 micron thick wet film and with the temperature at 72° F. and airmoving over the film at 110 feet per minute. More preferably, thebarrier coating dries in not longer than about 15 minutes, and mostpreferably not longer than about 10 minutes.

The following materials and combinations thereof can be useful in theweld maintenance coatings of the invention:

-   -   Minerals weld spatter does not adhere to:        -   a. Aluminum tri-hydroxide (AC712AN from Aluchem), magnesium            hydroxide (Magchem MH10 from Martin Marietta), graphite            (Graphite 1107 from Asbury graphite), Hexagonal BN (from            Carborundum)        -   b. Weld spatter adheres slightly: aluminosilicate            (TurboBrite from PQ Corporation), calcium carbonate            (Multiflex MM from Specialty Minerals), diatomaceous earth            (Diafil 570 from CR minerals Corporation), kaolin clay            (Wilklay RP-80, Wilklay RP-2 from Wilkinson Klay),            delaminated kaolin clay (Polyplate 90 and Polyplate HMT from            J M Huber), pumice (Pumice 5u from Hess Pumice), sodium            magnesium aluminosilicate, sodium aluminosilicate (Zeolex            94HP, Zeolex 98 from J M Huber)    -   Minerals with natural binding properties:        -   Calcium carbonate (Multiflex MM from Specialty minerals or            Socal 31 from Solvay), calcined clay (Huber 2000C from J M            Huber), delaminated kaolin clay (Polyplate 90 and Polyplate            HMT from J M Huber), sodium magnesium aluminosilicate,            sodium aluminosilicate (Zeolex 94HP, Zeolex 98 from J M            Huber), kaolin clay (Wilklay RP-80), talc (Ultratalc 609            from Specialty Minerals)    -   Minerals with fast dry time:        -   a. Less than 10 minutes (30% solution solids 250 micron dry            time) Sodium magnesium aluminosilicate, sodium            aluminosilicate (Zeolex 94HP, Zeolex 98 from J M Huber),            diatomaceous earth (Diafil 570 from CR Minerals            Corporation), magnesium hydroxide (Magchem MH 10 from Martin            Marietta), pumice (Pumice 5u from Hess Pumice)        -   b. Less than 15 minutes (30% solution solids 250 micron dry            time) aluminum tri-hydroxide (AC712AN from Aluchem)    -   Rheology control agents:        -   a. Anti-sagging, anti-settling and anti-synersis agents;            Bentone EW (Rheox), Multiflex MM-Socal 31, (Specialty            Minerals-Solvay Minerals), Veegum B (R. T. Vanderbilt),            Laponite RDS, Optibent M602 (Sud-Chemie), Cabosil M-5,            Attagel 50 (Engelhard)        -   b. Modify for spraying, brushing & rolling        -   Natrosol 330A (modified hydroxyethycellulose from Hercules),            Acrysol TT-615 (polyacrylic acid thickener from Rohm and            Hass)        -   c. Over-spray control        -   High molecular weight polyethylene oxide polymer (Polyox 308            from Union Carbide), Cyanamer A-370 (polyacrylamide from            Cytec Industries)    -   Fire retarding/smoke retarding ingredients:        -   a. Aluminum tri-hydroxide, borax, magnesium hydroxide,            antimony oxide    -   Anti-bacterial/anti-fungal additives:        -   a. CS-1135 from Angus chemical; Troysan 096, Proxel GXL    -   Binding agents:        -   a. Inorganic binders: hydrous sodium and potassium            polysilicates ranging from 1.0 to 3.22 mole ratio of            SiO₂/Na₂O for sodium polysilicates and 1.6 to 2.5 mole ratio            of SiO₂/K₂O (available from PQ Corporation).        -   b. Organic binding agents: wax emulsions Michelman 43040            (Michem Emulsions), lecithin, ethyleneoxide/propyleneoxide            block polymers (Pluronics from BASF), ethyl polysilicates            (Sibond 40 from Huls AG)    -   Defoamers and deaerators:        -   Colloid 640 (defoamer from Rhodia), Foamaster 111 (defoamer            from Cognis additives)    -   Colorants for product:        -   Iron oxides: Mapico 218M red iron oxide and Mapico 2150            yellow iron oxide (from Laporte Pigments red, yellow and            black iron oxides)        -   Graphite, carbon black, and ceramic pigments from Ferro            Corporation    -   Freeze prevention:        -   Ethylene glycol, propylene glycol, MP-Diol, glycerin    -   Anti skinning agents:        -   Propylene glycol, ethylene glycol, MP-Diol, glycerin    -   Dispersing agents:        -   a. Inorganic: Hydrous sodium polysilicate (Britesil C20),            trisodium phosphate, tetra potassium pyrophosphate (Solutia)        -   b. Organic: Nopcosperse 44, Tamol 731, lecithin    -   Flash rust and corrosion inhibitors:        -   a. Flash rusting, CS 1135 from Angus Chemical,        -   b. Corrosion inhibitor: J-0806 zinc phosphate from Laporte            Pigments.

Other materials that can be useful in the weld maintenance coatings ofthe invention can be found in reference materials relating to coatings,such as in “Paint and Coatings Raw Materials Handbook” authored byMichael and Irene Ash, or other similar handbooks.

The weld maintenance coating is applied to the welding machine by anysuitable method. The welding machine to be coated is well cleanedremoving as much weld slag as possible. The weld maintenance coating isapplied to the machine, especially in areas of high weld slag build up.The coating is typically spray applied. Air atomized, airless,air-assisted airless and high volume low pressure atomizing equipmentcan be used to apply the coating to the machine. A dry film of 20-120micron (130-800 microns wet) is the preferred dry film applicationthickness, more preferably from 30-60 micron dry films (200-400 micronswet). All electronic position sensors, welding tips and if preferredpart locator pins are wiped clean before the coating dries. After thecoating is dry the machine may be used. After weld slag has again builtup on the machine, the weld slag is removed by wire brushing, scraping,prying, or chiseling. The weld maintenance coating is removed along withthe weld slag. The weld maintenance coating is reapplied repeating theabove maintenance cycle.

EXAMPLES

The following examples for the welding machine maintenance coating wereevaluated by MIG welding over steel panels producing weld spatter thatadhered to the steel panel that can only be removed by grinding. Thespatter produced was also allowed to contact the maintenance coating onthe steel panel. Ingredients A B C D E F G Water 69.11 69.48 75.81 60.5269.75 55.60 46.80 Britesil C20 4.63 0.53 10.66 37.60 Bentone EW 1.260.74 1.63 0.85 1.48 Laponite RDS 0.32 Cabosil M-5 0.94 Natrosol Plus 3300.19 CS-1135 0.16 .08 0.11 .09 0.09 Colloid 640 defoamer 0.21 .08 0.12Igepal CO-630 0.32 0.27 Lecithin 2.23 Rhodopon BOS 0.38 Zeolex 94HP20.24 25.71 17.25 Ac-712AN 29.62 10.25 1.27 8.70 17.07 Magchem MH1029.78 Multiflex MM 2.83 2.46 Hubercarb Q-6 4.96 J-806 Zinc Phosphate0.80 0.25 0.7 Vansil W-30 0.88 Wilklay RP-80 14.88 Mapico 218 Red ironoxide 0.17 Mapico 2150 Yellow iron 0.13 oxide Raven H20 Carbon black0.01 Black Iron Oxide HB 1033T 2.98 Total 100 100 100 100 100 100 100

In example A, water and Bentone EW were added and mixed thoroughly for15 minutes on a cowles disperser. The mineral aluminum tri-hydroxide(AC712AN from Aluchem) was added and mixed under good mixing. Thematerial had a viscosity of 78 KU (Krebs units) and pH of 9.82. A 250micron wet film dries in 15 minutes. The binding properties of a wetfilm of 200 microns cast on a 6 inch by 12 inch by 0.032 inch unpolishedbare steel panel gives a dry film of approximately 30 microns. This dryfilm takes 50 finger double rubs to get to the substrate. For thepurpose of this invention binding properties are defined by using adouble rub process similar in procedure to ASTM D5402 MEK Double Rubs,commonly used to determine the cure or solvent resistance of an organiccoating film where you would soak a cloth with MEK (methyl ethyl ketone)and double rub the lacquer coating by hand until you reached thesubstrate, then record the number of double rubs. Finger double rubsrecorded is the number of rubs required to rub through the coating tothe substrate with no solvent or water used.

In example B, water and Bentone EW were added and mixed thoroughly for15 minutes on a cowles disperser. The mineral magnesium hydroxide(Magchem MH 10 from Martin Marietta) was added and mixed under goodmixing. Example B had a viscosity of 65 KU (Krebs Units) and a pH of10.1. A 250 micron wet film dries in 10 minutes. The dry film ofapproximately 30 microns takes 20 finger double rubs to get to thesubstrate. From observation, films that can withstand spatter impact andstill be easily removable by brushing or scraping rub down to thesubstrate with 50 to 200 finger double rubs at 30 microns dry film.Films that have less than 50 finger double rubs are too powdery towithstand much spatter impact for extended periods of time.

In examples A and B, these materials produced barrier coatings that weldspatter did not adhere to. That is, the weld spatter on the coating iseasily removed with no cohesive removal of the coating. Heating thesteel panel (with the coating applied) with a propane torch untilred-hot (approximately 1000 F for one inch diameter spot) for about aminute did not produce any fumes or smoke. When the films were dryingthey caused flash rusting of the steel. Flash rust is an oxidation ofthe steel that occurs, within minutes, as the water or water-bornecoating is drying. The slurries would upon setting separate into phases.

In the following example C, an organic dispersant/binding agent was used(lecithin). Water and Bentone EW were added, mixed thoroughly forfifteen minutes, and the wetting agent, dispersant/binding agent andantibacterial were added (Igepal CO-630, lecithin, and CS-135respectively). The minerals Hubercarb Q6 (calcium carbonate from J MHuber) and Wilklay RP-80 (kaolin clay from Wilkinson Klay) were addedand mixed under high shear. Example C had a viscosity of 61 KU (KrebsUnits) and pH of 8.79. A 250 micron wet film dries in 24 minutes (68°F., 110 feet per minute average air flow, 42% humidity). The bindingproperty of a film of approximately 30 microns dry film takes 43 fingerdouble rubs to get to the substrate. The weld spatter adhered veryslightly to the areas of the panel coated with the above coating. Whatis meant by very slight adhesion is the weld spatter would come off thecoated substrate easily but there would be some cohesive removal of thecoating with the weld spatter. Some unpleasant fumes were produced uponheating a coated steel panel with a propylene torch until red-hot.

Example C is marginally acceptable as a weld maintenance coating. It'son the borderline of acceptability for odor, weld spatter adhesion, filmbinding properties, product dry time, flash rusting of steel, and shelfstability. Example C is close to the upper limit of organic content thatis acceptable in a weld maintenance coating. (Example C has 2.71% byweight of organic material.) For this invention what is described asorganic material is anything that is known to decompose or combustproducing noxious fumes to 1300 C. The film is almost acceptable forfilm binding properties, being somewhat powdery giving 43 finger doublerubs to the substrate. The dry time of 24 minutes for 250 microns withmoving air (110 feet per minute) is marginal for in practice wet filmsof 1000 microns can be applied in areas on machinery. At 1000 micronswet film the dry time extrapolates to 96 minutes with moving air. 96minutes is much longer than the typical dry time window of one hour.Also often, there is very little moving air around the weldingmachinery. Lack of air movement extends the dry time considerably. Forexample, this same material at the same temperature and humidity withair flow less than 5 feet per minute has a 45-minute dry time for a180-micron wet film. This would extrapolate to a 4-hour dry time for a1000 micron wet film, which is unacceptable. This material produced somelight flash rusting on steel. It contains no flash rust inhibitingminerals. Upon setting, this material would separate into two phaseswith a clear liquid phase on the surface of the unmixed material. It isdesirable to have a one-phase material that would not require mixingbefore use.

In example D, this formulation contains minerals that in our testingprovide fast dry at room temperature with good binding properties(sodium magnesium aluminum silicate Zeolex 94HP), is a higher solidsformulation which speeds up dry time, and uses sodium polysilicate(britesil C20 from PQ Corporation) as an inorganic bindingagent/dispersant for the film. For weld spatter release it uses aluminumtri-hydroxide (AC712AN from Aluchem), and for flash rusting of metal thecorrosion inhibitor zinc phosphate is used. For rheology control andstability Natrosol Plus 330 (Hercules) and Multiflex MM from SpecialtyMinerals (or an equivalent such as Socal 31 from Solvay minerals) areused. In can preservatives to prevent bacterial and fungal growth(CS-1135 from Angus chemical), and a defoamer (Colloid 640 from Rhodia)are also used.

In example D, water, Natrosol plus 330, CS 1135, Igepal CO-630, andColloid 640 were added under agitation to a high shear cowles disperser.The minerals Zeolex 94 HP, AC712AN, Multiflex MM, and J-0806 ZincPhosphate were added and mixed with high shear with a cowles disperser.Example D had a viscosity of 80 KU (Krebs Units), a pH of 11.78, and arheology that prevents the material from sagging or running on verticalservices when applied. The sagging test is performed by applying a 200micron wet coating film to a steel panel, drawing a streak through thewet film with a pencil eraser, then setting the panel up vertically andobserving if the wet coated film runs down the panel past the streakproduced with the pencil eraser. The coating passes the test when thewet film stays above the streak produced with the eraser. A 250 micronwet film dries in 20 minutes (74° F., <5 feet per minute average airflow, 39% Humidity). The binding property of a film of approximately 30microns dry film takes 120 finger double rubs to get to the substrate.The weld spatter adhered very slightly to the areas of the panel coatedwith the above coating. Some slight fumes were produced upon heating acoated steel panel with a propylene torch until red-hot. In comparisonto example C, the fumes were much less in odor and quantity. The totalorganic content of this formulation is 0.66%.

In example E, this formulation is a more complete formulation addressingissues of odor (very little organic content (0.11% CS-1135)), weldspatter adhesion (Ac-712AN), film binding properties, product dry time,flash rusting of metal (zinc phosphate and calcium meta silicate),rheology control and stability (Bentone EW, Laponite RDS), in canpreservatives to prevent bacterial and fungal growth (CS 1135), andcolorants (red and yellow iron oxides and carbon black) for the product.Water, britesil C20, Bentone EW, Laponite RDS (from Southern ClayProducts) and CS-1135 were added then mixed for a half hour with goodshear mixing with a cowles disperser mixer. Zeolex 94HP, AC-712AN,J-0806 zinc phosphate, and Vansil W-30 were added under good high shearmixing. The colorants were also added to give a brown color. Example Ehas a viscosity of 84 KU (Krebs units) and rheology that prevents thematerial from sagging or running on vertical services when applied.Other physical properties are a pH of 11.78 and the material has a lightbrown color. A 250 micron wet film dries in 7½ minutes (73° F. 90 feetper minute average air flow, 39% humidity). The binding properties of awet film of 200 microns cast on a 6 inch by 12 inch unpolished baresteel panel gives a dry film of approximately 30 microns. It takes 200finger double rubs to get to the substrate. MIG welding over this steelpanel produced weld spatter that adhered to the steel panel that canonly be removed by grinding. The weld spatter did not adhere to theareas of the panel coated with the above coating. No noticeable fumes orsmoke was produced on heating a coated steel panel with a propylenetorch until red-hot.

In example F, a higher solids formulation addresses issues of odor (verylittle organic content 0.17%), weld spatter adhesion (Ac-712AN), flashrusting of metal (zinc phosphate), rheology control and stability(Bentone EW,), in can preservatives to prevent bacterial and fungalgrowth (CS 1135), and colorants (black iron oxide HB1033T from HooverColor Corporation) for the product. Water, Zeolex 94HP, AC-712AN,Multiflex MM, J-0806 zinc phosphate, black iron oxide HB1033T, CS-1135,and Colloid 640 were added then mixed for a half hour with good shearmixing with a cowles disperser mixer. Bentone EW and Britesil C2.0 wereadded under good high shear mixing. Example F has a viscosity of 72 KU(Krebs units) and rheology that prevents the material from sagging orrunning on vertical surfaces when applied. Other physical properties area pH of 11.50 with a gray color upon drying. A 250 micron wet film driesin 6 minutes (73° F. 90 feet per minute average air flow, 59% humidity).The binding properties of a wet film of 200 microns cast on a 6 inch by12 inch unpolished bare steel panel gives a dry film of approximately 30microns. It takes 200 finger double rubs to get to the substrate. MIGwelding over this steel panel produced weld spatter that adhered to thesteel panel that can only be removed by grinding. The weld spatter didnot adhere to the areas of the panel coated with the above coating. Nonoticeable fumes or smoke was produced on heating a coated steel panelwith a propylene torch until red-hot.

Example F was also spray applied to welding machinery using high volumelow pressure spray equipment. It took 13 minutes to spray apply thecoating. The coating was dry to touch in 20 minutes at 70° F., 77%humidity with air movement ranging from 50-130 FPM. This coating wasfound to slow the build up of weld spatter and what spatter that didbuild up was found to be easily removable. Four months after coatingapplication with the welding machinery in production use the coating wasstill providing weld spatter release by slowing the buildup of weldspatter.

In example G, this formulation is translucent (semi-transparent)allowing the colors of painted portions of the automated machinery toremain visible. Water, Britesil C20, Cabosil M-5 (Cabot Corporation),CS-1135, Colloid 640, Rhodopon BOS (Rhone poulenic), and AC-712AN wereadded then mixed for a half hour with good shear mixing with a cowlesdisperser mixer. Example G has a viscosity of 60 KU (Krebs units). Ithas an organic content of 0.59% of the formulation. Other physicalproperties are a pH of 11.7, and the material is a white liquid dryingto a translucent film where color markings are still visible through thefilm. A 250 micron wet film dries in 30 minutes. The binding propertiesof a wet film of 200 microns cast on a 6 inch by 12 inch unpolished baresteel panel gives a dry film of approximately 30 microns. It takes morethan 200 finger double rubs to get to the substrate. At 200 fingerdouble rubs the substrate was only slightly rubbed away. MIG weldingover this steel panel produced weld spatter that adhered to the steelpanel that can only be removed by grinding. The weld spatter did notadhere to the areas of the panel coated with the above coating. Nonoticeable fumes or smoke was produced on heating a coated steel panelwith a propylene torch until red-hot.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiments. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.For example, although this invention has been described primarily interms of a welding machine maintenance coating, the invention is notlimited to use on welding machines. Rather, the invention is a barriercoating which is useful for coating any surface to prevent the adhesionof an unwanted material on the surface. Some nonlimiting examples ofuses for the barrier coating include preventing any type of materialthat cures up or otherwise solidifies on a surface from adhering to thesurface, such as adhesives, sealers, solders, brazing compounds, andothers.

1-21. (canceled)
 22. A manufactured slurry for forming a barrier coatingto prevent a material from adhering to a surface, the slurry comprisinga mineral material in water, the slurry containing from about 10% toabout 70% solids by weight and not more than 1% by weight of a materialthat fumes or smokes when heated to 1000° F. for one minute; the slurrywhen dried forming the barrier coating that binds to the surface suchthat at least about 50 finger double rubs are required to reach thesurface when the dry barrier coating is 30 microns thick.
 23. A slurryaccording to claim 22 wherein the barrier coating is a welding machinemaintenance coating to prevent weld spatter from adhering to thesurface.
 24. A slurry according to claim 22 wherein the slurry includesa plurality of mineral materials.
 25. A slurry according to claim 22wherein the slurry contains substantially no material that fumes orsmokes when heated to 1000° F. for one minute.
 26. A slurry according toclaim 22 wherein the slurry is sprayable.
 27. A slurry according toclaim 22 wherein the slurry has a rheology that prevents the slurry fromsagging or running on a vertical surface when applied at a temperatureof 72° F.
 28. A slurry according to claim 22 wherein the slurry containssubstantially no organic solvent.
 29. A manufactured slurry for forminga barrier coating to prevent a material from adhering to a surface, theslurry comprising a mineral material in water, the slurry containingfrom about 10% to about 70% solids by weight and not more than 1% byweight of a material that fumes or smokes when heated to 1000° F. forone minute; the slurry when dried forming the barrier coating, anddrying in a time not longer than about 15 minutes when the slurry isapplied as a 250 micron thick wet film and with the temperature at 73°F., 59% humidity, and air moving over the film at 90 feet per minute.30. A slurry according to claim 29 wherein the barrier coating is awelding machine maintenance coating to prevent weld spatter fromadhering to the surface.
 31. A slurry according to claim 29 wherein theslurry includes a plurality of mineral materials.
 32. A slurry accordingto claim 29 wherein the slurry contains substantially no material thatfumes or smokes when heated to 1000° F. for one minute.
 33. A slurryaccording to claim 29 wherein the slurry is sprayable.
 34. A slurryaccording to claim 29 wherein the slurry has a rheology that preventsthe slurry from sagging or running on a vertical surface when applied ata temperature of 72° F.
 35. A manufactured slurry for forming a barriercoating to prevent a material from adhering to a surface, the slurrycomprising water, a mineral material, and a rheology control agentselected from the group consisting of anti-sagging, anti-settling andanti-synersis agents, the slurry containing from about 10% to about 70%solids by weight and not more than 1% by weight of a material that fumesor smokes when heated to 1000° F. for one minute.
 36. A slurry accordingto claim 35 wherein the slurry further includes a rust inhibitor.
 37. Aslurry according to claim 35 wherein the barrier coating is a weldingmachine maintenance coating to prevent weld spatter from adhering to thesurface.
 38. A slurry according to claim 35 wherein the slurry includesa plurality of mineral materials.
 39. A slurry according to claim 35wherein the slurry contains one or more mineral materials selected fromthe group consisting of aluminum tri-hydroxide, magnesium hydroxide,graphite, hexagonal boron nitride, and mixtures thereof.
 40. A slurryaccording to claim 35 wherein the slurry contains one or more mineralmaterials selected from the group consisting of sodium magnesiumaluminosilicate, diatomaceous earth, pumice, amorphous silica, andmixtures thereof.
 41. A slurry according to claim 35 wherein the slurrycontains one or more mineral materials selected from the groupconsisting of calcium carbonate, calcined clay, delaminated kaolin clay,kaolin clay, talc, and mixtures thereof.